Bangladesh Virus Research Articles

First Report of Tomato Leaf Curl Bangladesh Virus Associated with Leaf Yellowing Symptoms in Lablab purpureus in Bangladesh

First Report of Tomato Leaf Curl Bangladesh Virus Associated with Leaf Yellowing Symptoms in <i>Lablab purpureus</i> in Bangladesh

DIVERSITY, MUTATION AND PHYLOGENETIC ANALYSIS OF PEPPER LEAF CURL LAHOREVIRUS AND PEPPER LEAF CURL BANGLADESH VIRUS INFECTING CHILI CROP

Since a few decades ago, the pandemic of the Chilli Leaf Curl Disease Complexes (ChiLCD) has caused enormous alarm. The investigations of various genomes isolated from various regions of the subcontinent in the current study revealed a vast expansion of ChiLCD. According to evolutionary research, genomes from the pepper leaf curl Lahore virus (PepLCLV) (JN880419 and JX524173) and the pepper leaf curl Bangladesh virus (PepLCBV) (DQ116881 and KY420149) are ancestors while others are descendants. The accessions JN880419, JX524173, DQ116881, and KY420149's sequences underwent evolution, giving rise to several strains and variations. According to the findings, the Indian subcontinent's chilli crop may be most severely affected by the extremely aggressive ChiLCV.

Identification of a novel variant of hepatitis B virus isolated from patient co-infected with hepatitis C virus

Hepatitis B virus (HBV) is a major public health concern worldwide. Co-infection of hepatitis B patients with other pathogens intensifies the severity of the disease. We report a novel variant of hepatitis B virus (HBV) in Bangladesh isolated from a patient co-infected with hepatitis C virus (HCV) who exhibited liver cirrhosis. From 150 collected plasma samples, we sequenced HBV complete genome from one HBV-HCV co-infected patient. The complete genome was analysed using bioinformatics tools, NCBI BLAST, Geno2Pheno, and SnapGene software. The strain belongs to genotype A and subgenotype A1. Upon analysing the complete genome of this strain, we found a frameshift deletion of 54 nucleotides at the pre-S2 region, a functional regulator of HBV surface protein. Furthermore, we observed a Y126H mutation in the polymerase protein of this strain. This is the first report with such an unusual pre-S deletion event of the HBV genome in an HCV-co-infected patient associated with liver cirrhosis. These findings may inform scientists about genomic modifications in the HBV genome associated with HCV co-infection.

Correction to: First report of Citrus tristeza virus in Bangladesh

Correction to: First report of Citrus tristeza virus in Bangladesh

Climate Anomalies and Spillover of Bat-Borne Viral Diseases in the Asia-Pacific Region and the Arabian Peninsula.

Climate variability and anomalies are known drivers of the emergence and outbreaks of infectious diseases. In this study, we investigated the potential association between climate factors and anomalies, including El Niño Southern Oscillation (ENSO) and land surface temperature anomalies, as well as the emergence and spillover events of bat-borne viral diseases in humans and livestock in the Asia–Pacific region and the Arabian Peninsula. Our findings from time series analyses, logistic regression models, and structural equation modelling revealed that the spillover patterns of the Nipah virus in Bangladesh and the Hendra virus in Australia were differently impacted by climate variability and with different time lags. We also used event coincidence analysis to show that the emergence events of most bat-borne viral diseases in the Asia–Pacific region and the Arabian Peninsula were statistically associated with ENSO climate anomalies. Spillover patterns of the Nipah virus in Bangladesh and the Hendra virus in Australia were also significantly associated with these events, although the pattern and co-influence of other climate factors differed. Our results suggest that climate factors and anomalies may create opportunities for virus spillover from bats to livestock and humans. Ongoing climate change and the future intensification of El Niño events will therefore potentially increase the emergence and spillover of bat-borne viral diseases in the Asia–Pacific region and the Arabian Peninsula.

First report of Citrus tristeza virus in Bangladesh

In Bangladesh, citrus is an important fruit crop that is becoming more commonly cultivated in commercial plantations. In March 2019, we observed yellowing, vein clearing, and mild mosaic symptoms in citron (Citrus medica). Based on systematic serological and molecular analyses of the symptomatic leaf samples, the Citrus tristeza virus (CTV) was identified. To the best of our knowledge, this is the first report of CTV and any citrus virus in Bangladesh.

Mathematical analysis of a COVID-19 model with double dose vaccination in Bangladesh

COVID-19 is an infectious disease that kills millions of people each year and it is a major public health problem around the globe. The current COVID-19 situation is still now concerning, though the vaccination program is running. In this study, we considered a COVID-19 model with a double-dose vaccination strategy to control the current outbreak situation in Bangladesh. The fundamental qualitative analysis of this mathematical model has been performed. The conditions of positive invariance, boundedness with suitable initial conditions were analyzed. We have estimated the basic reproduction number (R0) for disease transmission and determined that our model contains two equilibrium points: the disease-free equilibrium and a disease-endemic equilibrium. We used the Routh-Hurwitz criteria to determine the stability of the equilibria. The disease will be eradicated from the community if R0 < 1, otherwise the disease persists in the population. To support the qualitative analysis of our model, we performed numerical simulations using MATLAB routine and estimated model parameters. Sensitivity analysis is used to explore the association for Mild and Critical cases concerning the corresponding model parameters. We observed that the most significant parameter to spread the virus is the transmission rate. The numerical simulations showed that a full dose vaccination program significantly reduces the mild and critical cases and has potential impact to eradicate the virus from the community. The information that we generated from our analysis may help the public health professionals to impose the best strategy effectively to control the outbreak situation of the virus in Bangladesh.

Circulating Phylotypes of White Spot Syndrome Virus in Bangladesh and Their Virulence.

White Spot Syndrome Virus (WSSV) has emerged as one of the most prevalent and lethal viruses globally and infects both shrimps and crabs in the aquatic environment. This study aimed to investigate the occurrence of WSSV in different ghers of Bangladesh and the virulence of the circulating phylotypes. We collected 360 shrimp (Penaeus monodon) and 120 crab (Scylla sp.) samples from the south-east (Cox’s Bazar) and south-west (Satkhira) coastal regions of Bangladesh. The VP28 gene-specific PCR assays and sequencing revealed statistically significant (p < 0.05, Kruskal–Wallis test) differences in the prevalence of WSSV in shrimps and crabs between the study areas (Cox’s Bazar and Satkhira) and over the study periods (2017–2019). The mean Log load of WSSV varied from 8.40 (Cox’s Bazar) to 10.48 (Satkhira) per gram of tissue. The mean values for salinity, dissolved oxygen, temperature and pH were 14.71 ± 0.76 ppt, 3.7 ± 0.1 ppm, 34.11 ± 0.38 °C and 8.23 ± 0.38, respectively, in the WSSV-positive ghers. The VP28 gene-based phylogenetic analysis showed an amino-acid substitution (E→G) at the 167th position in the isolates from Cox’s Bazar (referred to as phylotype BD2) compared to the globally circulating one (BD1). Shrimp PL artificially challenged with BD1 and BD2 phylotypes with filtrates of tissue containing 0.423 × 109 copies of WSSV per mL resulted in a median LT50 value of 73 h and 75 h, respectively. The in vivo trial showed higher mean Log WSSV copies (6.47 ± 2.07 per mg tissue) in BD1-challenged shrimp PL compared to BD2 (4.75 ± 0.35 per mg tissue). Crabs infected with BD1 and BD2 showed 100% mortality within 48 h and 62 h of challenge, respectively, with mean Log WSSV copies of 12.06 ± 0.48 and 9.95 ± 0.37 per gram tissue, respectively. Moreover, shrimp antimicrobial peptides (AMPs), penaeidin and lysozyme expression were lower in the BD1-challenged group compared to BD2 challenged shrimps. These results collectively demonstrated that relative virulence properties of WSSV based on mortality rate, viral load and expression of host immune genes in artificially infected shrimp PL could be affected by single aa substitution in VP28.

Pepper leaf curl Bangladesh virus

This datasheet on Pepper leaf curl Bangladesh virus covers Identity, Distribution, Vectors &amp; Intermediate Hosts, Further Information.

Genetic variability and evolutionary dynamics of atypical Papaya ringspot virus infecting Papaya.

Papaya ringspot virus biotype-P is a detrimental pathogen of economically important papaya and cucurbits worldwide. The mutation prone feature of this virus perhaps accounts for its geographical dissemination. In this study, investigations of the atypical PRSV-P strain was conducted based on phylogenetic, recombination and genetic differentiation analyses considering of it’s likely spread across India and Bangladesh. Full length genomic sequences of 38 PRSV isolates and 35 CP gene sequences were subjected to recombination analysis. A total of 61 recombination events were detected in aligned complete PRSV genome sequences. 3 events were detected in complete genome of PRSV strain PK whereas one was in its CP gene sequence. The PRSV-PK appeared to be recombinant of a major parent from Bangladesh. However, the genetic differentiation based on full length genomic sequences revealed less frequent gene flow between virus PRSV-PK and the population from America, India, Colombia, other Asian Countries and Australia. Whereas, frequent gene flow exists between Pakistan and Bangladesh virus populations. These results provided evidence correlating geographical position and genetic distances. We speculate that the genetic variations and evolutionary dynamics of this virus may challenge the resistance developed in papaya against PRSV and give rise to virus lineage because of its atypical emergence where geographic spread is already occurring.

The Concentration of 25-Hydroxy Vitamin D in Chronic Liver Disease and its’ Correlation with Severity

Chronic Liver Disease (CLD) is a common disease all over the world and the major biological factors are Hepatitis B virus (HBV) and Hepatitis C virus (HCV) in Bangladesh and Alcoholic liver disease in the western world. Life expectancy of CLD patient is increasing now a days by available modern treatment; but the long term complications are now evident. Hepatic osteodystrophy is one of the most common complication which is associated with vitamin D deficiency. Vitamin D undergoes hepatic 25-hydroxylation, but as the hepatic parenchyma is jeopardized so the metabolic activation of this vitamin is impaired. The aim of the study was to measure the concentration of 25-hydroxy vitamin D 25(OH) D in CLD patient in different etiology and to find out the relationship of level of 25(OH) D in different stages of the disease according to Child-Pugh classification. This cross sectional study was carried out in the Department of Gastroenterology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka during the period of April 2015 to March 2016. Patients attending the Gastroenterology Department with cirrhosis of liver and who fulfilled the inclusion criteria were initially enrolled for the study. Study objectives were explained and informed consent was taken from patients prior to record their clinical history, examination findings and initial investigation reports in the standard data sheet. The diagnosis of liver cirrhosis was made by combination of clinical features, blood profile and trans abdominal ultrasonography (T. USG). Endoscopy of the upper GIT was also done to see the presence of oesophageal or gastric varices which is a sign of increase portal pressure. Stages of CLD were assessed by Child-Pugh scoring system and level of 25(OH) D was measured from blood with the help of the Department of Bio-chemistry. Data was collected using a structured data sheet and analyzed by SPSS. Out of 85 patients, male-female ratio was 3:1 and mean age was 53.0 ± 10.7 year within the range of 25-70 years. Most of the patients had acites 92.9% and anorexia 90.6%; where four-fifth patients had weight loss and more than one third had Jaundice. Nearly half of the patients had abdominal pain and 42.4% had melaena. Four-fifth patients had history of blood transfusion and most of them had H/O hospitalization 94.8%, anaemia (97.6%) and Splenomegaly 92.9%. More than half (52.9%) of patients had bone pain; where jaundice 61.2% and Leukonychia 61.2% were detected in equal number of patients. Mean vitamin 25(OH) D was 16.29 ± 7.96 in 69 HBV patients and 20.14 ± 9.76 in 16 HCV patients. In this study, 28.2% patients were in child Pugh A, 36.4% in child Pugh B and 32.9% in child Pugh C stages. Mean vitamin 25(OH) D were 27.12 ± 6.11, 15.97 ± 5.40 and 9.57 ± 1.I5 in Child-pugh A, Child-pugh B and Child-pugh C stages respectively. Mean vitamin 25(OH) D was observed at decreased level as the changes of stage from lower to higher. Vitamin D deficiency was highly prevalent in patients with CLD and inversely correlated with disease severity. In the case of chronic liver diseases, vitamin D seems to modulate the innate and adaptive immune system, which explains the association. This study suggest that these parameters may improve with vitamin D supplementation. Monitoring of S. 25(OH) D is reasonable in CLD patient.&#x0D; Bangladesh Med J. 2020 Sept; 49(3) : 35-42

Molecular characterization of SARS-CoV-2 from Bangladesh: implications in genetic diversity, possible origin of the virus, and functional significance of the mutations

In a try to understand the pathogenesis, evolution and epidemiology of the SARS-CoV-2 virus, scientists from all over the world are tracking its genomic changes in real-time. Genomic studies can be helpful in understanding the disease dynamics. We have downloaded 324 complete and near complete SARS-CoV-2 genomes submitted in GISAID database from Bangladesh which were isolated between 30 March to 7 September, 2020. We then compared these genomes with Wuhan reference sequence and found 4160 mutation events including 2253 missense single nucleotide variations, 38 deletions and 10 insertions. The C>T nucleotide change was most prevalent (41% of all mutations) possibly due to selective mutation pressure to reduce CpG sites to evade CpG targeted host immune response. The most frequent mutation that occurred in 98% isolates was 3037C>T which is a synonymous change that usually accompanied 3 other mutations that include 241C>T, 14408C>T (P323L in RdRp) and 23403A>G (D614G in spike protein). The P323L was reported to increase mutation rate and D614G is associated with increased viral replication and currently most prevalent variant circulating all over the world. We identified multiple missense mutations in B-cell and T-cell predicted epitope regions and/or PCR target regions (including R203K and G204R that occurred in 86% of the isolates) that may impact immunogenicity and/or RT-PCR based diagnosis. Our analysis revealed 5 large deletion events in ORF7a and ORF8 gene products that may be associated with less severity of the disease and increased viral clearance. Our phylogeny analysis identified most of the isolates belonged to the Nextstrain clade 20B (86%) and GISAID clade GR (88%). Most of our isolates shared common ancestors either directly with European countries or jointly with middle eastern countries as well as Australia and India. Interestingly, the 19B clade (GISAID S clade) was unique to Chittagong, which was originally prevalent in China. This reveals possible multiple introductions of the virus in Bangladesh via different routes. Hence, more genome sequencing and analysis with related clinical data is needed to interpret functional significance and better predict the disease dynamics that may be helpful for policy makers to control the COVID-19 pandemic.

Explorando el conocimiento, la conciencia y las prácticas de COVID-19 entre los dentistas en Bangladesh: una investigación transversal.

Background: COVID-19 pandemic has caused an unpre-cedented strike on humanity around the world . The scenario in Bangladesh is getting worse day by day, and every aspect of the society is observing its impact. Health care professionals are at a greater risk of contracting the disease while caring for patients. Objective: The research objective is to explore knowledge, awareness, and practices of registered dentists regarding COVID-19 epidemiology and transmission during the rapid outbreak of this highly contagious virus in Bangladesh. Material and Methods: A cross-sectional web-based survey was conducted among the dentists who were enrolled with their valid unique Bangladesh Medical and Dental Council (BMDC) registration number. A structured questionnaire was distributed among the dentists through different social media platforms. A total of 184 dentists participated in the survey between March and April 2020. Both descriptive analysis and multivariable logistic regression analysis was performed. Results: The dentists' mean age was 31.75 years, with a standard deviation of 6.5 years. About 29.3% of dentists completed their postgraduate qualification, and 76% of them were engaged in private practice at the time of data collection. Compared to the dentists with undergraduate education, the dentists with a postgraduate education are three times (OR=3.1, 95%CI 1.2-7.9 and over 5 times (OR=5.3, 95% CI: 1.2-23.3) more likely to have) better knowledge and practices toward COVID-19 respectively. Dentists aged 26-30 years are less likely to have good practices than the younger dentists (OR: .1; 95% CI: .01-.5). However, dentists with less than five years experience are 10.3 (1.6-68.9) times more likely to have good practices compared to the dentists with more experience. Conclusion: Majority of the dentists from Bangladesh have shown good knowledge, awareness, and practice regarding COVID-19. We recommend that the healthcare authorities, professional organizations, and hospitals coordinate, and conduct mandatory advanced infectious disease training for all the practicing dentists in the country.

First molecular characterization and phylogenetic analysis of the VP2 gene of feline panleukopenia virus in Bangladesh.

Feline panleukopenia virus (FPV) is a highly contagious infectious pathogen of cats globally. However, there is no information on the molecular identification and characterization of FPV in Bangladesh. Here, 8.16% (8/98) and 18.37% (18/98) of diarrheic cats tested positive for FPV by an immunochromatography (IC) test and PCR, respectively. The IC test showed 44.44% sensitivity and 100% specificity in comparison with PCR. Our newly sequenced Bangladeshi FPV strain (MN826076) showed the highest (99.71%) sequence identity to strains from the United Arab Emirates (UAE). Strain MN826076 contained two characteristic amino acid variations in VP2 identifying it as an FPV strain: valine at position 103 and aspartic acid at position 323. Phylogenetically, the VP2 of strain MN826076 was found to be closely related to 19 FPV strains, sharing the same clade.

Molecular Analysis of SARS-CoV-2 Circulating in Bangladesh during 2020 Revealed Lineage Diversity and Potential Mutations.

Virus evolution and mutation analyses are crucial for tracing virus transmission, the potential variants, and other pathogenic determinants. Despite continuing circulation of the SARS-CoV-2, very limited studies have been conducted on genetic evolutionary analysis of the virus in Bangladesh. In this study, a total of 791 complete genome sequences of SARS-CoV-2 from Bangladesh deposited in the GISAID database during March 2020 to January 2021 were analyzed. Phylogenetic analysis revealed circulation of seven GISAID clades G, GH, GR, GRY, L, O, and S or five Nextstrain clades 20A, 20B, 20C, 19A, and 19B in the country during the study period. The GISAID clade GR or the Nextstrain clade 20B or lineage B.1.1.25 is predominant in Bangladesh and closely related to the sequences from India, USA, Canada, UK, and Italy. The GR clade or B.1.1.25 lineage is likely to be responsible for the widespread community transmission of SARS-CoV-2 in the country during the first wave of infection. Significant amino acid diversity was observed among Bangladeshi SARS-CoV-2 isolates, where a total of 1023 mutations were detected. In particular, the D614G mutation in the spike protein (S_D614G) was found in 97% of the sequences. However, the introduction of lineage B.1.1.7 (UK variant/S_N501Y) and S_E484K mutation in lineage B.1.1.25 in a few sequences reported in late December 2020 is of particular concern. The wide genomic diversity indicated multiple introductions of SARS-CoV-2 into Bangladesh through various routes. Therefore, a continuous and extensive genome sequence analysis would be necessary to understand the genomic epidemiology of SARS-CoV-2 in Bangladesh.

Geographical Modules of COVID-19 Pandemic in Bangladesh: Social Response and Action Taken

Objectives: This research attempts to figure out a comparative pattern of the social response from the peoples of Bangladesh as well as different communities and regarding actions taken by the government during the COVID-19 pandemic in Bangladesh. Else, this study also investigates the shortcomings of the different wing authorities of the Bangladesh Government to reach people of every corner of this country. Methods: In this research, different facts are analyzed from a statistical point of view. Authentic sources like reputed national and international newspapers, governmental release documents, release notes of WHO, etc. were considered for data collection to realize this country’s preparations against the COVID-19 pandemic. Results: From the statistical analysis, this study found that different government authorities partially failed to communicate the measures of the government to the wider public audience. This study has shown that having more tests could have prevented the spread of the virus in Bangladesh. The strong lockdown measures taken by the government were not enough as the population of this country is huge and it is really difficult to maintain social distance in a densely populated country like Bangladesh. Conclusions: The socio-economic condition and decision-makers’ shortcomings could have been overcome if the right plan and action had been taken at the right time. Until the vaccine is available it is recommended that people should keep social distance while going outside, using masks and protection should be mandatory. Furthermore, more health care professionals should be hired and trained to fight this virus. Doi: 10.28991/SciMedJ-2021-03-SI-4 Full Text: PDF

Efficacy of two vaccines against recent emergent antigenic variants of clade 2.3.2.1a highly pathogenic avian influenza viruses in Bangladesh

H5N1 highly pathogenic avian influenza viruses (HPAIVs) have caused outbreaks in poultry in Bangladesh since 2007. While clade 2.2.2 and 2.3.4.2 HPAIVs have not been detected since 2012, clade 2.3.2.1a viruses have caused continuous outbreaks since 2012 despite the use of vaccines. In this study, we evaluated the efficacy of two H5 vaccines licensed in Bangladesh, RE-6 inactivated vaccine, and a recombinant herpesvirus of turkeys vaccine with an H5 insert (rHVT-H5), for protection against recent field viruses in chickens. We selected three viruses for efficacy tests (A/chicken/Bangladesh/NRL-AI-3237/2017, A/crow/Bangladesh/NRL-AI-8471/2017 and A/chicken/Bangladesh/NRL-AI-8323/2017) from 36 H5 viruses isolated from Bangladesh between 2016 and 2018 by comparing the amino acid sequences at five antigenic sites (A-E) and analyzing hemagglutination inhibition (HI) titers with reference antisera. The RE-6 and rHVT-H5 vaccines both conferred 80–100% clinical protection (i.e. reduced morbidity and mortality) against the three challenge viruses with no significant differences in protection. In addition, both vaccines significantly decreased viral shedding from infected chickens as compared to challenge control chickens. Based on these metrics, the current licensed H5 vaccines protected chickens against the recent field viruses. However, the A/crow/Bangladesh/NRL-AI-8471/2017 virus exhibited antigenic divergence including: several unique amino acid changes in antigenic epitope sites A and B and was a serological outlier in cross HI tests as visualized on the antigenic map. The continuing emergence of such antigenic variants which could alter the dominant antigenicity of field viruses should be continuously monitored and vaccines should be updated if field efficacy declines.

Detection of Mumps Virus of Genotype G in Bangladeshi Children Suffering from Encephalitis

Although mumps virus (MuVi) is an important agent of encephalitis, however, mumps vaccine has not yet been included in the national immunization programme of Bangladesh. Furthermore, the genotype distribution of this virus in Bangladesh is unknown. Cerebrospinal fluid samples collected from 97 children with encephalitis from April 2009 to March 2010 were subjected to polymerase chain reaction (PCR) test to determine the causative agents. MuVi was detected in two samples, these samples were further subjected to conventional PCR using specific primers, then amplicons were sequenced, and genotype was determined as genotype G. Phylogenetic analysis showed that these strains were clustered with strains from Nepal, India, the UK, Thailand, and the USA. By Bayesian inference, we also determined that the ancestor of Bangladeshi and Indian MuVi were same and segregated only about two decades back. These results will help future surveillance and the detection of invading MuVi strains from other countries.

Genetic and biological characterization of Newcastle disease viruses circulating in Bangladesh during 2010-2017: further genetic diversification of class II genotype XIII in Southcentral Asia.

Newcastle disease virus (NDV) is endemic in Bangladesh and is a major threat to commercial poultry operations. While complete fusion (F) genes are recommended for molecular characterization and classification of NDV isolates, heretofore, only partial F gene data have been available for Bangladeshi NDVs. To this end, we obtained the full-length F gene coding sequences of 11 representative NDVs isolated in Bangladesh between 2010 and 2017. In addition, one of the viruses (MK934289/chicken/Bangladesh/C161/2010) was used in an experimental infection of chickens to establish the viral pathotype and study gross and microscopic lesions. Phylogenetic analysis provided evidence that all studied Bangladeshi isolates belong to genotype XIII.2 of class II NDVs. Six of the viruses were isolated between 2010 and 2017 and grouped together with isolates from neighbouring India during 2013-2016. Another four Bangladeshi isolates (2010-2016) formed a separate monophyletic branch within XIII.2 and showed high nucleotide distance from the isolates from India and the other six Bangladeshi viruses within the sub-genotype; however, none of these groups fulfils all classification criteria to be named as a separate sub-genotype. The eleventh Bangladeshi virus studied here (C162) was genetically more distant from the remaining isolates. It out-grouped the viruses from sub-genotypes XIII.2.1 and XIII.2.2 and showed more than 9.5 % nucleotide distance from all genotype XIII sub-genotypes. This isolate may represent an NDV variant that is evolving independently from the other viruses in the region. The experimental infection in chickens revealed that the tested isolate (C161) is a velogenic viscerotropic virus. Massive haemorrhages, congestion and necrosis in different visceral organs, and lymphoid depletion in lymphoid tissues, typical for infection with velogenic NDV, were observed. Our findings demonstrate the endemic circulation of sub-genotype XIII.2 in Southcentral Asia and further genetic diversification of these viruses in Bangladesh and neighbouring India. This constant evolution of the viruses may lead to the establishment of new genetic groups in the region. Additional historical and prospective virus and surveillance data from the region and neighbouring countries will allow a more detailed epidemiological inference.

The Ecology of Nipah Virus in Bangladesh: A Nexus of Land-Use Change and Opportunistic Feeding Behavior in Bats.

Nipah virus is a bat-borne paramyxovirus that produces yearly outbreaks of fatal encephalitis in Bangladesh. Understanding the ecological conditions that lead to spillover from bats to humans can assist in designing effective interventions. To investigate the current and historical processes that drive Nipah spillover in Bangladesh, we analyzed the relationship among spillover events and climatic conditions, the spatial distribution and size of Pteropus medius roosts, and patterns of land-use change in Bangladesh over the last 300 years. We found that 53% of annual variation in winter spillovers is explained by winter temperature, which may affect bat behavior, physiology, and human risk behaviors. We infer from changes in forest cover that a progressive shift in bat roosting behavior occurred over hundreds of years, producing the current system where a majority of P. medius populations are small (median of 150 bats), occupy roost sites for 10 years or more, live in areas of high human population density, and opportunistically feed on cultivated food resources—conditions that promote viral spillover. Without interventions, continuing anthropogenic pressure on bat populations similar to what has occurred in Bangladesh could result in more regular spillovers of other bat viruses, including Hendra and Ebola viruses.